On QRP-L there has recently been some discussion of the effectiveness of small loop antennas. Some hams in Northern Italy are doing something very interesting in this area. They have two identical QRP (1 watt) QRSS transmitters on 30 meters. They are keyed simultaneously, but one antenna is connected to a standard vertical antenna (with a very good radial system), while the other goes to a small, resonant CFA loop. By looking at the various QRSS on-line grabbers out there, you can get a real sense of how the two antennas perform. I just took at look at VK6DI's grabber -- I could clearly see the signal from the vertical, and could see quite a bit of the signal from the loop (see above at around 10140040 -- the loop signal is a few Hz above).
Claudio, I2NDT, has a good web page describing the experiment:
http://digilander.libero.it/i2ndt/pagine/Dual%20Beacon.htm
What's a CFA antenna? Couldn't find much when I gooogled it.
ReplyDeleteThat experiment sounds intersting Bill. What is nice about using a loop antenna is that you don't have to worry about sparks jumping across the tuning capacitor with 20mw. :)
ReplyDeleteAlan